Objective: To describe the magnitude of immune restoration after long-term control of HIV-1 replication. DESIGN Prospective study of immune restoration in patients starting highly active antiretroviral therapy (HAART).
Methods: Patients with moderately advanced HIV-1 infection (CD4 cells between 100 x 10 and 300 x 10 /l) who enrolled in a trial of HAART and who had suppression of HIV-1 replication during 3 years of therapy were evaluated for phenotypic and functional indices of immune restoration.
Results: Almost all immune restoration achieved occurred during the first year. The median CD4 lymphocyte count increased by 159 x 10 cells/l during the first year (P < 0.001); CD4 lymphocyte rises during the second and third years were not significant. Most decreases in activation antigen expression (CD38/HLA-DR) on CD4 and CD8 lymphocytes occurred during the first year, and after 3 years, patient lymphocytes were still abnormally activated. The proportion of CD4 lymphocytes expressing CD28 increased during the first and second years, but even after 3 years, CD28 expression on CD4 cells remained abnormally low. Lymphocyte proliferative responses to normalized during the first 12 weeks of HAART while responses to tetanus increased only after immunization and enhanced responses to HIV-1 p24 antigen were not observed.
Conclusions: Immune restoration was incomplete in patients who started HAART with moderately advanced HIV-1 disease and most changes occurred during the first year. These data suggest that this degree of suppression of HIV-1 replication alone will not suffice to restore immune competence. The clinical significance of incomplete reconstitution of CD4 lymphocyte number, phenotype, and proliferative function in HIV-1 infection remains to be determined.